It will be closed all the time without the engine running. The spring heats up and lessens the tension when running. Either the stop is missing or it is assembled incorrect.

It will be closed all the time without the engine running. The spring heats up and lessens the tension when running. Either the stop is missing or it is assembled incorrect.

After looking at it further, I think you are correct in that the stop is missing. The stop should hold the plate in the closed position when cold, and the spring when heated, will open the plate 90 degrees. What is happening now is that the spring allows the plate to move 180 degrees, back to the open position.

Thanks for your input. Now I just have to figure out what it is that should be stopping it in the closed position.

There was a stop pin that had to be there before assembley of the riser. I think if you research pictures you will see the pin that's needed. Does the manifold have the stamped steel counter weight or the round cast counter weight? There is a difference on how they look?

Mine has the heavy round counter weight. I looked everywhere for a stop pin where one should be, but found no sign of one. I was thinking of drilling a hole on the counter weight and putting in a roll pin that would stop the assembly from going past the closed position. I simulated this buy sticking a small open end wrench inside the exhaust hole that held the plate in the closed position and heated up the weight and bi metal spring and it worked perfectly. It allowed the plate to be moved to full open at around 300 degrees. And as it cooled, it was fully closed again at around 200 degrees.

I don't know how to find any pictures of where the factory pin should be. If you know of any, please post or send a link.

Thanks!

It should look something like this.

Yes, exactly like that.

I think I know what is missing. A spring steel piece that goes in next to the bi-metal spring that limits the travel of the plate. I have a picture but I can't figure out how to post it.